Is Cybertron the only Transformers planet the creators had seeded?
If yes, does that mean Lockdown is a Cybertronian? Or is he an independent custom rendition of the Creators?
Within Age of Extinction itself, there is no direct evidence that Cybertron was seeded.
There is, however, evidence of other planets being seeded - including Earth.
Cade: Wait. The Seed?
Tessa: Those nasty soldiers that were chasing us. I saw them board the ship and they took something that they called the seed.
Hound: Listen. Sixty million years ago, give or take an eon...
Optimus: Thousands of planets were cyber-formed with Seeds. They turned your organic life into our elemental metals. Our creators destroyed your world to make us.
Whether or not Lockdown is a Cybertronian is left unspecified within the movie, but he has one quote that makes it sound as though he at least pre-dates the two factions.
Lockdown: Autobots, Decepticons, like little children: always fighting, making a mess out of the universe. Then I've got to clean it up.